HI, great video. just one comment if I may :) . This just want to be constructive criticism, or a simple advise as you wish :) . When you measured the RMS noise with the fluke 287, you decided to use a 50ohm adapter so that the fluke shows the correct RMS value. This is probably very wrong. You should never modify the circuit to display correct values on the display of equipment, especially in modern equipment such as fluke287 and TG2511A. By adding the adapter in your system you affect the performance of the circuit you are measuring. To make an analogy is like you want to measure the depth of a swimming pool by diving, but you cannot reach the bottom so you destroy it and you build it less deep so you can measure its depth. Anyway, in you particular case, the signal generator is set to display a value, which would be correct if it is closed on a load of 50ohm. Now, if your load is not 50 ohm but 10Mohm (your voltmeter), then your modern signal generator can be setup for this situation. You should push the button "OUTPUT" in your signal generator and set "HIGH-Z", which means high impedance. Now your signal generator should match the measurement of your voltmeter and we got this result without using any 50ohm adapter. So in short the device who is wrong in your connection voltemeter-signal generator is not the voltmeter but the signal generator display, which has to be set correctly in order to display the correct measurement. For more information on how to use electronic equipment, look at the manual of your signal generator and try to give a look to any videolecture about a basic electronic course. :) Said that, keep up with your videos. In our field, we never stop to learn.
at 10 megaohms the fluke is reading the same signal twice, doubling the original thru reflection. Either way should be accurate, change the pathway or change the starting signal. The original signal voltage is the correct reading, any meters that come down the line need to match the starting point, imo.
I have the earlier version with the "Nuvistor" in the impedance converter. It's been a great meter for noise measurements but I need to do a though re-capping and alignment, some of the internal calibration adjustments are nearly at their stops. However it's still within spec and is flat +/- 2-3% from 10 Hz to 10 MHz. Mine has option 001, this moves the dB scale to the top and provides a dB scale from +2 to -15dB in .2dB increments. I also have a HP 400E, this is more or less a fully solid sate version with a FET in place of the Nuvistor. Thanks for the video :)
The Racal 9300 is also another useful device . You need to be mind full of the bandwidth , I would only trust a meter up to 10MHz. Spectrum analysers have optimised square filters for measuring noise.
Good video, Martin. I LOVE those old RMS voltmeters. I've collected several over the years (HP, Ballantine, bruel & kjaer, Fluke and Boonton), and they stand ready on a shelf in my lab. They cost a kings ransom in their day -- I think the bruel & kjaer was over $3k USD in the 80's. Imagine a day when these were bleeding edge, and you go back in a time machine with a Fluke 289 😆.
In the military I used one of those meters daily measuring Voice Circuits. We had all those cool toys.
@Frankie Bleddyn Telecommunications Tech Control . 307x0
@Frankie Bleddyn Yep, PMEL . We sent chit to them about every other week I think.
HI, great video. just one comment if I may :) . This just want to be constructive criticism, or a simple advise as you wish :) . When you measured the RMS noise with the fluke 287, you decided to use a 50ohm adapter so that the fluke shows the correct RMS value. This is probably very wrong. You should never modify the circuit to display correct values on the display of equipment, especially in modern equipment such as fluke287 and TG2511A. By adding the adapter in your system you affect the performance of the circuit you are measuring. To make an analogy is like you want to measure the depth of a swimming pool by diving, but you cannot reach the bottom so you destroy it and you build it less deep so you can measure its depth. Anyway, in you particular case, the signal generator is set to display a value, which would be correct if it is closed on a load of 50ohm. Now, if your load is not 50 ohm but 10Mohm (your voltmeter), then your modern signal generator can be setup for this situation. You should push the button "OUTPUT" in your signal generator and set "HIGH-Z", which means high impedance. Now your signal generator should match the measurement of your voltmeter and we got this result without using any 50ohm adapter. So in short the device who is wrong in your connection voltemeter-signal generator is not the voltmeter but the signal generator display, which has to be set correctly in order to display the correct measurement. For more information on how to use electronic equipment, look at the manual of your signal generator and try to give a look to any videolecture about a basic electronic course. :) Said that, keep up with your videos. In our field, we never stop to learn.
at 10 megaohms the fluke is reading the same signal twice, doubling the original thru reflection. Either way should be accurate, change the pathway or change the starting signal. The original signal voltage is the correct reading, any meters that come down the line need to match the starting point, imo.
I have the earlier version with the "Nuvistor" in the impedance converter. It's been a great meter for noise measurements but I need to do a though re-capping and alignment, some of the internal calibration adjustments are nearly at their stops. However it's still within spec and is flat +/- 2-3% from 10 Hz to 10 MHz. Mine has option 001, this moves the dB scale to the top and provides a dB scale from +2 to -15dB in .2dB increments. I also have a HP 400E, this is more or less a fully solid sate version with a FET in place of the Nuvistor. Thanks for the video :)
The Racal 9300 is also another useful device . You need to be mind full of the bandwidth , I would only trust a meter up to 10MHz. Spectrum analysers have optimised square filters for measuring noise.
Mjlorton, what is the best way to know my meter’s revision
Here is a dedicated probe for this type of work:
ruclips.net/video/d_Ybe6xnMIg/видео.html
Mjlorton, how do I find out what revision my meter is?
You promised link to Dave Jones's video, I can not find the link.
m.ruclips.net/video/Edel3eduRj4/видео.html
There is no link to Jones' video mentioned.
Good video, Martin. I LOVE those old RMS voltmeters. I've collected several over the years (HP, Ballantine, bruel & kjaer, Fluke and Boonton), and they stand ready on a shelf in my lab. They cost a kings ransom in their day -- I think the bruel & kjaer was over $3k USD in the 80's. Imagine a day when these were bleeding edge, and you go back in a time machine with a Fluke 289 😆.
Would the 3400a be a good choice for alignment of the if section of an am or fm radio?